IO::GD::write_gif_anim for better GIF animation in Demos/harness

Changes

@@ -8,6 +8,7 @@
 - fix Transform::Proj4 tests and build (#498 #499) - thanks @shawnlaffan
 - t_linear stores iunit ounit itype otype
 - IO::FITS no longer writes COMMENT header with "HASH(0x...)"
+- add IO::GD::write_gif_anim for better GIF animation in Demos/harness
 
 2.093 2024-09-29
 - PDL.set_datatype now doesn't physicalise input, PDL.convert_type does

Demos/harness

@@ -1,5 +1,6 @@
 use strict; use warnings;
 use PDL;
+use PDL::IO::GD; # for write_gif_anim, bigger file but nicer looking
 use PDL::Demos;
 use File::Path qw(mkpath);
 use File::Spec::Functions qw(catdir catfile splitpath updir);
@@ -109,7 +110,7 @@ for (@infos) {
         if (@this_imgs > 1) {
           my $multiframe = cat(map rpic($_), @this_imgs);
           my $vidfile = catfile($outdir, "vid-".++$vidcounter.".gif");
-          $multiframe->wmpeg($vidfile);
+          $multiframe->write_gif_anim($vidfile, 0, 10);
           unlink @this_imgs;
           delete @seen_img{@this_imgs}; # may reappear with new content
           @this_imgs = $vidfile;

IO/GD/GD.pd

@@ -396,6 +396,53 @@ loop(i) %{
 EOC
 );
 
+pp_def( 'write_gif_anim',
+        Pars => 'img(c=3,x,y,n)',
+        GenericTypes => ['B'],
+        OtherPars => 'char* filename; int Loops; int Delay',
+        OtherParsDefaults => {Loops=>0, Delay=>4},
+        NoPthread => 1,
+        Doc => <<'EOF',
+=for ref
+
+Writes an image cube to a file as an animated GIF.
+
+RGB dimension is first. y=0 is at bottom. 0 loops = infinite (default).
+Delay in 100ths of a second, default 4.
+EOF
+        Code => <<'EOF',
+FILE *fh = fopen($COMP(filename), "wb");
+if (!fh) $CROAK("Error opening %s\n", $COMP(filename));
+gdImagePtr im = gdImageCreateTrueColor($SIZE(x), $SIZE(y)), im_prev = NULL;
+if (!im) $CROAK("Error creating gdImage\n");
+loop (n=0:1) %{
+  loop (y,x) %{
+    gdImageSetPixel(im, x, $SIZE(y)-1-y,
+      gdImageColorResolve(im, $img(c=>0), $img(c=>1), $img(c=>2))
+    );
+  %}
+%}
+gdImageGifAnimBegin(im, fh, 0, $COMP(Loops));
+gdImageGifAnimAdd(im, fh, 1, 0, 0, $COMP(Delay), gdDisposalNone, im_prev);
+im_prev = im;
+loop (n=1) %{
+  im = gdImageCreateTrueColor($SIZE(x), $SIZE(y));
+  if (!im) $CROAK("Error creating gdImage\n");
+  loop (y,x) %{
+    gdImageSetPixel(im, x, $SIZE(y)-1-y,
+      gdImageColorResolve(im, $img(c=>0), $img(c=>1), $img(c=>2))
+    );
+  %}
+  gdImageGifAnimAdd(im, fh, 1, 0, 0, $COMP(Delay), gdDisposalNone, im_prev);
+  gdImageDestroy(im_prev);
+  im_prev = im;
+%}
+gdImageDestroy(im_prev);
+gdImageGifAnimEnd(fh);
+fclose(fh);
+EOF
+);
+
 pp_addxs( <<'ENDXS' );
 void 
 _gdImageDestroy( im )